### Author Topic: RMF calculation VS Manual calculation  (Read 1279 times)

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#### wise318

• Jr. Member
• Posts: 20
##### RMF calculation VS Manual calculation
« on: September 22, 2011, 08:10:38 AM »
Hi, I have 2 wheeled drive robot here is the spec
total Mass of robot = 20 kg
Desired velocity= 1 m/s
Desired acceleration =2m/s

From torque calculation = F. R = ma.Radius = 20 x 2 x 0.05 = 2 Nm

should it be divided by 2 so 1 Nm per motor ?

In other words I should get the motor that has 1 Nm

Q2. How inaccurate this calculation in sizing the motor?If I use RMF calculation I could not derived the torque, I should need to find the motor 1st and get the input torque then put inside the calculator, Where my difficulties the vendor is asking me what is the torque you need, So i need the calculated torque, Please give me an advice ya

Q3 In the calculator on excel, it said " if you have twice the motors, then they just need half the output ", should i divide the RMF by 2 ?

#### wise318

• Jr. Member
• Posts: 20
##### Re: RMF calculation VS Manual calculation
« Reply #1 on: September 24, 2011, 07:32:22 AM »
Hi, I have 2 wheeled drive robot here is the spec
total Mass of robot = 20 kg
Desired velocity= 1 m/s
Desired acceleration =2m/s

From torque calculation = F. R = ma.Radius = 20 x 2 x 0.05 = 2 Nm

should it be divided by 2 so 1 Nm per motor ?

In other words I should get the motor that has 1 Nm

Q2. How inaccurate this calculation in sizing the motor?If I use RMF calculation I could not derived the torque, I should need to find the motor 1st and get the input torque then put inside the calculator, Where my difficulties the vendor is asking me what is the torque you need, So i need the calculated torque, Please give me an advice ya

Q3 In the calculator on excel, it said " if you have twice the motors, then they just need half the output ", should i divide the RMF by 2 ?

#### waltr

• Supreme Robot
• Posts: 1,944
##### Re: RMF calculation VS Manual calculation
« Reply #2 on: September 24, 2011, 08:26:56 AM »
Did you try using the RMF calculator found in the Robot Tutorials above?
This has two parts:
1- the required RMF to move to Bot.
2- the RMF produced by a motor.

#### wise318

• Jr. Member
• Posts: 20
##### Re: RMF calculation VS Manual calculation
« Reply #3 on: September 25, 2011, 11:15:07 AM »
Did you try using the RMF calculator found in the Robot Tutorials above?
This has two parts:
1- the required RMF to move to Bot.
2- the RMF produced by a motor.

This is the summary

RMF   13.9
RMF (zero incline)   13.9
Momentum      20
Motor Rotation Speed   382
Energy/second   1.76   Watts

Torque   0.1 kgm
Speed    200 rps
Motor RMF    20   (as above)

yes it is pretty the same as theoritical but my question do i need divide by 2, in my theoritical calculation to get 1 NM

#### waltr

• Supreme Robot
• Posts: 1,944